Abstract
Two extracellular proteolytic enzymes from Staphylococcus aureus, strain V8, were separated by isoelectric focusing. One protease, with an isoelectric point at pH 4.0 (protease I) was purified 185-fold by negative adsorption on CM-Sephadex, isoelectric focusing and gel chromatography on Sephadex G-75. The molecular weight of this enzyme was about 21 000. The pH-optimum was at 7.8 using casein as the substrate, and at 5.0 and 7.0–9.0 using hemoglobin as the substrate. The activity of protease I was not significantly affected by divalent cations, metal-chelating agents, sulfhydryl reagents, or by diisopropylfluorophosphate. The other protease with an isoelectric point at 9.4 (protease II) was purified 310-fold by negative adsorption on DEAE-Sephadex, isoelectric focusing and gel chromatography on BioGel P 60. The molecular weight was 12 500. The pH optimum was at pH 8.8. Protease II was only active in the presence of reducing agents, and was inactivated by heavy metals. Protease II exhibited esterase activity, using N- benzoyl- l - tyrosine ethyl ester as the substrate.
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